The drive in 2I:1:7 has failed, controller did not detect new drive when it was inserted in bay 7. Rebooting server with new drive inserted did not help. It might be some backplane issue.

As it's remote location I've instructed the local person to insert the new drive into bay 4.

But I'm not abe to modify this array:

=> ctrl slot=0 array B add spares=1I:1:4
Error: This operation is not supported with the current configuration. Use the
"show" command on devices to show additional details about the
configuration.
Reason: Array is transforming

=> ctrl slot=0 array B modify drives=1I:1:4,2I:1:5,2I:1:6,2I:1:8
Error: This operation is not supported with the current configuration. Use the
"show" command on devices to show additional details about the
configuration.
Reason: Array is transforming